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Nantlle Railway, site of
Nantlle to Caernarfon, Gwynedd, Wales, UK
Nantlle Railway, site of
associated engineer
George Stephenson
Robert Stephenson senior
date  1825 - 1828
UK era  Georgian  |  category  Railway  |  reference  SH475603
photo  Wagon, National Slate Museum, by Dan Crow [Author] GFDL, via Wikimedia Commons
The narrow gauge horse-drawn Nantlle Railway, also known as the Nantlle Tramway, was the first public railway in north Wales, built to carry slate to the port of Caernarfon. Later it also operated as a passenger service and part of the line was relaid as standard gauge for steam locomotives. Now dismantled, traces are still visible alongside the modern Welsh Highland Railway. One narrow-gauge section was the last operating British Rail horse-drawn line.
First proposed in 1813, the line was constructed to transport slate from quarries to the north and west of Nantlle to the quays at Caernarfon for export. This avoided a long and costly road journey, enabling Nantlle’s quarries to compete with business from the much larger ones at Dinorwic (SH586604) and Penrhyn (SH621649). The 14.5km route meandered westwards from various branches connecting the Nantlle quarries, to Talysarn and Penygroes, where it turned northwards, winding past Groeslon, Llanwnda, Dinas and Bontnewydd.
The Act incorporating the Nantlle Railway Company was passed on 20th May 1825. Working capital of £20,000 in £100 shares was raised under its provisions. Most of the shareholders were local quarry owners. The company’s chief engineer was George Stephenson (1781-1848) and the line was laid out by his brother Robert Stephenson (1788-1837), who supervised the work assisted by John Gillespie.
Though private tramways already existed at many quarries and collieries, this was the first purpose-built public line for the quarrying industry. The Nantlle Railway Company didn't operate its own railroad. Instead, the line was in effect a railway toll road, charging fees for haulage. As well as slate, it also carried copper, from the mine at Drws-y-coed (SH545534) east of Nantlle.
The company was permitted to charge "6d [2.5p] per ton per mile" for transporting metal, ore or slate, and "3d [1.25p] per ton per mile" for other goods. Once the interest "and other current expenses" were paid, and sufficient money raised to pay a share dividend of 5%, the 6d tonnage rate was supposed to be reduced to 3.5d (1.46p).
During construction, two more Acts were passed. On 21st March 1827, a second Bill authorised the raising of £70,000 by mortgaging the works, and not reducing the tonnage duties until all the debts were paid. On 23rd May 1828, a third Bill allowed a further five years in which to finish the project.
Among the structures on the line are a 120m long embankment (SH476603) with culvert west of Bontnewydd (see map), two tunnels laid to curves, and a bridge. The short Coed Helen Tunnel (SH481616) carried the railway under a road, with a gentle rising gradient from north to south. Its walls and roof are of coursed blocks, some up to 1.3m long. The semicircular arched portals are of coursed rubble with single row voussoirs.
Plas Dinas Tunnel (SH481593) carried the line under the driveway to Plas Dinas house. It is 45.1m long, 2.45m wide and about 1.75m high, with a semicircular arched roof of three rings of brick supported by stone rubble walls. The portals are approximately 3m high and 3.8m wide, constructed of rough squared blocks and rubble, and approached by cuttings 10.8m deep.
The single arch Afon Gwyrfai Bridge (SH480599) carried the railway over the Afon Gwyrfai, west of Bontnewydd. From a survey on 26th February 1992, it is 6.15m wide at the base and narrower at the crown (inaccessible), with a span of 15.3m between approach embankments up to 4.5m high (south side). Its arch is 4.6m from the springing, or approximately 5.6m above water level, and constructed in rusticated stone blocks 700mm deep.
The railway track was initially of lightweight wrought iron fish-bellied rails, later replaced with flat-bottomed rails. It was constructed to a gauge of 1.067m (3ft 6in), presumably chosen by the company, apparently to Robert Stephenson’s dismay. This is wider than the 610mm (2ft) gauge of most quarry tramroads but narrower than the 1.435m (4ft 8.5in) that would become the steam railway network’s standard gauge, largely as a result of George Stephenson’s efforts.
The Nantlle line’s single track had 22 passing bays but no signalling. Trains progressed from one passing place to the next by line of sight, with heated debates if opposing trains met between bays. The strings of wagons, four or five pulled by a single horse, typically travelled at the walking pace of the person leading the horse ‐ 3.2-4.8kph (2-3mph). The wagons each had four external double-flanged wheels with metal plated bodies bolted to the axles.
From 11th August 1856 to 12th June 1865, the Nantlle Railway carried passengers. Timetables were imposed to allow passenger trains to run at speeds of 9.7-11.3kph (6-7mph), and goods trains were restricted to operating in convoy, morning and evening, so most of the passing places were removed.
In 1862, the Carnarvonshire Railway took over the line between Penygroes and Caernarfon. It installed a standard gauge track south from Caernarfon to Afon Wen, east of Pwllheli, closely following the Nantlle Railway’s route to Penygroes but bypassing the Afon Gwyrfai Bridge, which was abandoned. After the new line opened to passenger and freight services on 2nd September 1867, the remaining section of narrow gauge track was used as a feeder to the standard gauge one. Slate had to be transferred from one line to the other at Penygroes, adding to the export costs.
On 4th July 1870, the Carnarvonshire Railway was absorbed into the London & North Western Railway (L&NWR). In 1871, the L&NWR took over the Nantlle Railway from Penygroes to Talysarn and converted it to standard gauge for steam locomotive working. At Talysarn, the line passed beneath a tall slate slab bridge known as Pont Fawr (SH494532). On 1st October 1872, a new terminus (SH487529) opened for passenger services, located south of Talysarn around 3km west of Nantlle.
However, the easternmost section of the Nantlle Railway, from Talysarn to Pen-yr-Orsedd Quarry (SH509541), survived at its original narrow gauge. It remained a horse-drawn railway until closure as recently as 1963, making it British Railways’ last line to use horse traction. The rails were removed some time after 1967.
In September 1999, the Afon Gwyrfai Bridge was Grade II listed. It has suffered some loss of stonework in the arch spandrels, and the approach embankments have been breached for farm access and residential roads. The south portal of Plas Dinas Tunnel has collapsed.
Resident engineer: Robert Williams of Bangor
Contractor: William Owen of Gwaenfynydd, Anglesey
Contractor: Robert Stephenson senior and John Gillespie
RCAHMW_NPRN 569, 41448, 309267, 309269
Research: ECPK
"The Archaeology of an Early Railway System: The Brecon Forest Tramroads" by Stephen Hughes, Royal Commission on the Ancient and Historical Monuments of Wales, 1990
"George and Robert Stephenson: The Railway Revolution" by L.T.C. Rolt, Penguin Books Ltd, London, 1984
"George Stephenson: The Engineer & His Letters" by W.O. Skeat, The Institution of Mechanical Engineers, London, 1973
"The Slate Industry and Transport in North-West Wales" by Charles E. Lee, Transactions of the Newcomen Society, Harlech, 28th May 1962
"Historical Account of the Navigable Rivers, Canals, and Railways, of Great Britain" by Joseph Priestley, Longman, Rees, Orme, Brown & Green, London and Richard Nichols, Wakefield, 1831

Nantlle Railway, site of